Make a confirmation popupp on "meld av" button.

[GerhardGustavsen]

Is your feature request related to a problem? Please describe.
Students have been complaning about acendentaly signingthemselvs off events by misclicking.

Describe the solution you'd like
A simple popupp with a "are you shure" butten.

Describe alternatives you've considered
Maby sending an confirmation email, but i doubt people wuld want the span and i think it wil be less effective.